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Your Essential Guide To SBEM Calculations

essential guide to sbem calculations assessments

A high priority within the building industry is to find ways to create greener, more sustainable developments. As a result, energy efficiency is a high priority in the UK.

Energy assessments are carried out to ensure that new buildings are:

  • Well insulated
  • Well ventilated
  • Efficiently heated, cooled and lit
  • Sustainable

SBEM Calculations: The Basics

SBEM is a computer program. It provides an analysis of a building’s energy consumption. It calculates monthly energy use and carbon dioxide emissions of a building, using a description of the building geometry, construction, use and HVAC and lighting equipment.

SBEM calculations were originally based on the Dutch methodology NEN 2916:1998 (Energy Performance of Non-Residential Buildings). It has since been modified to comply with current UK building regulations.

SBEM: Key Facts

  • SBEM stands for the Simplified Building Energy Model and has been available in the UK since 2006.
  • SBEM calculations are required for commercial buildings, whilst SAP calculations are for dwellings.
  • Sustain Quality offers both SBEM and SAP calculations, depending on your specific requirements.
  • In order to produce a new or up-to-date Energy Performance Certificate (EPC), you need to carry out SBEM calculations. It is against the law to rent or sell a commercial property without an EPC.
  • The EPC rates the property between 1 and 100. The closer to 100 the rating is, the more energy-efficient the building is.
  • SBEM calculations come in two formats: L2A (new builds) and L2B (conversions and extensions) and contribute to a new or updated Energy Performance Certificate (EPC).

As Design and As Built Stage

‘As Design’ and ‘As Built’ refers to the construction stage of a development. SBEM calculations are important during both ‘as design’ and ‘as built’ stage due to a number of factors which we will explore below.  

As Design

The design stage SBEM assessment should be completed prior to the construction starting. During the As Design Stage, an SBEM calculation may anticipate any potential barriers in achieving compliance with Building Regulations.

We recommend that you do this early in the process as it will reduce your costs and will provide you with more flexibility regarding materials and energy-efficient systems used.

It is important to note that without a Design Stage SBEM calculation, building control bodies cannot allow construction on the commercial building to commence.

As Built

The as built SBEM calculation is carried out once the work has been completed. During the As Built Stage, it’s important that the SBEM calculation is carried out so that building control can sign the project off.

If alterations on the building have been carried out, this will be incorporated into the As Built SBEM calculation.

The property cannot be issued with an Energy Performance Certificate (EPC) until the SBEM calculation has passed the required targets.

What Details Do We Require?

The more information you give us prior to carrying out a calculation, the more accurate our assessment will be. Ideally, we’d like:

•            Full-scaled plans            

•            Building fabric details

•            Sections and elevations of the final or intended layout

•            Information on air tightness and thermal bridging

•            Specifications for heating, cooling, ventilation, hot water and lighting         

•            Any renewable systems to be installed

Click here for a copy of the appointment form we require you to complete prior to the assessment being carried out.

How Much Do SBEM Calculations Cost?

money saving money with sbem caluclations

When it comes to SBEM calculations, we get a lot of enquiries as to how much they cost. As you might have guessed, this figure will vary depending on the type of project and the individual requirements of the project.

Cost For The Design Stage

We offer SBEM calculations during both stages of the construction process. During the design stage, we carry out an SBEM calculation prior to the construction work being carried out.

This shows that the building meets the Target Emission Rate (TER) for efficiency.

An SBEM calculation at this stage would cost anything in the region of £350-£5,000 depending on the size of the development.

Cost For The ‘As Built’ Stage

Once works have been completed (the ‘as built’ stage), we will carry out another SBEM calculation.

The ‘as built’ SBEM calculation should be reflective of the calculation carried out during the ‘as design’ stage.

We aim to provide a detailed and comprehensive ‘as design’ SBEM calculation so that your work can be signed off by Building Control in a smooth and efficient manner.

A SBEM calculation at this stage would cost anything in the region of £350-£5,000 depending on the size of the development.

‘As Design’, ‘As Build’, Or Both?

We recommend that you get your SBEM completed as early as possible. We would suggest that you involve your assessor as part of the Design team in order to identify any shortfalls before they become a problem. 

In an ideal world, it would be great to stay with you throughout the process so that we can complete the SBEM calculations at both stages of the build. However, we understand that certain factors don’t allow for this.

For example, you might sell the building(s) before works have been completed. In this instance, it would be up to the new owner to organise a SBEM calculation. This may be months or even years down the line.

We recognise that there is a need for flexibility and our core aim is to assist and support in the smooth running of your building project.

What Are You Paying For?

Essentially, you are paying for our expertise, resources and time. We’re highly skilled in the latest, government approved energy assessment software and a large part of our work involves careful and strategic use of this software.

Factors Affecting Cost Of A SBEM Calculation

One of the main reasons that we suggest working closely alongside the design team is to avoid any factors that could affect the cost of a SBEM calculation.

Major changes in design may require another SBEM calculation to be carried out, which could take up more time and resources for all parties involved.

What Buildings Require An SBEM Calculation?

Every new building with a heating system will need to be assessed to check energy efficiency against current Government emission targets.

If you’re building a dwelling, such as houses or apartment blocks, it needs its own SAP calculation, whereas any building that isn’t a dwelling will require an SBEM calculation.

In simple terms, an SBEM calculation will be needed for all non-domestic, new-build properties.

What Does The Term ‘Non-Domestic’ Mean?

The term ‘non-domestic’ refers to any property that is not used as a place of permanent or semi-permanent residence. The most common example of a domestic building is, of course, a house.

Non-domestic buildings also refer to B&B accommodation and holiday homes which are let for 140 days or more a year.

Examples of non-domestic buildings include:

  • Shops
  • Offices
  • Factories
  • Schools
  • Warehouses
  • Pubs
  • Restaurants
  • Town halls

Domestic Buildings

Domestic buildings also need to demonstrate compliance with Building Regulations. The difference here is that an SAP calculation would be required, rather than an SBEM calculation. Sustain Quality provides both SAP and SBEM calculations, depending on the nature of your project.

A More In-Depth Exploration Of SBEM Buildings

Construction Of New Buildings, Other Than Dwellings

The obvious buildings are the ones listed above, but hospitals and hotels also require SBEM calculations to be carried out. 

When it comes to student accommodation and care homes, there is a certain element of confusion amongst some of our designers

Generally, if the living space is self-contained (as in, people have their own bedroom, kitchen, and bathroom facilities), an SAP calculation would be required.

SBEM calculations are required when there are shared areas, such as kitchens, lounges, and corridors.

If in doubt, talk to one of our experts today.

Fit-Out Works

An SBEM would be required if:

  • The fit-out work is part of the construction of a new building.
  • It is the first fit-out shell and core development where the shell is sold or let before fit-out work is carried out.

Extensions To Existing Buildings

An SBEM would be required if the extension to the existing building exceeds 100m2 and greater than 25% of the total floor area of the existing building.

Buildings That Contain Both Dwellings And Non-Dwellings

An example of this would be a block with shops on the ground floor and flats above. In this instance, an SBEM applies to the shop and common areas of the flats (stairwells and corridors). The flats will require an SAP calculation as it is classed as a non-commercial dwelling.

Living Accommodation and Commercial Purposes

Some buildings contain both living accommodation and space used for commercial purposes, the whole building should generally be treated as a dwelling, and therefore would require an SAP calculation.

This is based on the assumption that the commercial part could revert to living accommodation, and it doesn’t occupy a substantial portion of the total building. This doesn’t apply if there is a small bed-sit in a large office building!

Buildings That Are Exempt

We would always recommend that you contact Building Control in your local area before making any assumptions regarding exemption. However, below are the main exemptions.

Places Of Worship

Places of worship are exempt from SBEM, but if there are offices, catering facilities, etc adjoining these, they would not be exempt. In this instance, a part building calculation would be required.

Temporary Buildings

If a temporary building has a use time of fewer than two years, an SBEM calculation would not be required. If the temporary building exceeds this, you’d need to get your SBEM calculation booked in.

Buildings With Low Energy Demand

Examples of this are industrial sites, workshops, and agricultural buildings. The energy demand is concerning the energy for occupants, not an industrial or agricultural process.

Stand Alone Buildings

If the building has a total floor space of less than 50m2, then an SBEM calculation would not be required.

Distinguishing between those buildings that require SBEM or SAP calculations is the first step, before entering into the design process of your project.

How Are SBEM Calculations Made?

SBEM calculations come in two formats: L2A (new builds) and L2B (extensions and conversions). The primary purpose of the calculations is to produce a BRUKL (Building Regulations Part L) report in order to create a new or updated Energy Performance Certificate (EPC).

The SBEM Assessment: A Computer Program

We use details of your proposed site, for example, drawings, use of materials, building’s geometry, and construction, to make a prediction of your expected carbon emissions and monthly energy use.

This is a computer-based task and we use software known as iSBEM. The latest version of the software is known as version 4.1.a.

sbem calculations are carried out via a computer program

SBEM Calculations

Without getting too overly technical, the SBEM essentially completes a range of calculations to determine energy performance.

The programme combines the building’s description data to calculate the energy performance, split into different end-uses on a monthly basis. These are heating, cooling, lighting, ventilation, hot water, and auxiliary energy.

Weather Data

As well as the building’s geometry, Weather Data is also used. Weather Data consists of monthly values including outside dry-bulb temperature and solar radiation based on the TRY (Test Reference Years) for 14 UK locations. They are:

  • Belfast
  • Birmingham
  • Cardiff
  • Edinburgh
  • Glasgow
  • Leeds
  • London
  • Manchester
  • Newcastle
  • Norwich
  • Nottingham
  • Plymouth
  • Southampton
  • Swindon

Different Projects

Our approach will vary slightly depending on the nature of the project. If you require a site survey, we will visit you on sight, take measurements and prepare your SBEM calculation.

If your project is a new build or extension over 100m2 and you have completed scaled drawings, we will carry out a desk-based exercise and prepare your SBEM calculation for submission to building control.

For new builds, your SBEM calculations will be split into two reports: ‘design stage’ and ‘as built’. 

For extensions and conversions, L2B SBEM Calculations are split into ‘notional’ and ‘proposed’ reports.

How To Pass An SBEM Calculation

how to pass a sbem calculation

There are several criterions for Part L2A of the UK’s Commercial Building Regulations in order to pass an SBEM calculation which we will explore now.

It’s important to note that this is not a one-size-fits-all approach, but there are key areas that can make improvements to your results and are common across most non-domestic building types.

Demonstrating Compliance

BER<TER

The calculated CO2 emission rate (this is known as the BER-Building Emission Rate) must not be greater than the Target Emission Rate (TER).

This is the main requirement of Part L, and it is mandatory.

Fabric

Achieving a thermally efficient, air-tight building allows for greater flexibility regarding the specification of building services. However, if your project is under 500m2, it is exempt from an air permeability test.

You may choose to carry out a voluntary air test on smaller buildings. This may be a cost-effective way to hit emission targets.

Heating

It is recommended that you select a heating system compatible with the intended use of the building. This will ensure your route to compliance is straightforward.

A centralised heating system is the best option, and we recommend that you avoid localised electric heating unless absolutely necessary.

Opt for ground or air source heating if the building is not connected to a gas network.

Biomass or a Combined Heat and Power (CHP)

A Biomass or a Combined heat and power (CHP) are effective ways to simultaneously produce heat and electricity, capturing and utilising the heat that is a by-product of the electricity generation process.

By generating heat and power simultaneously, CHP can reduce carbon emissions by up to 30% compared to the separate means of conventional generation via a boiler and power station.

A Biomass and CHP does require a lot of space, so bear this in mind when considering heating options.

Warehouses and Spaces with High Ceilings

We recommend that for these applications, you consider radiant heating as it will warm people and objects, rather than increase air temperature. If traditional hot air systems are installed, we can install de-stratification fans to ensure an even temperature balance.

Ventilation And Cooling

Choose air conditioning cooling systems that are appropriate for the size of the space.

Consider strategies that focus on utilising thermal mass, heat gain control and heat dissipation along with natural ventilation.

Lighting

We recommend that you choose LED lighting applications due to their high efficiency and low expense.

In order to keep wasted energy to a minimum, couple the bulb section with an effective control system, utilising passive infra-red or photoelectrics.

Why Are SBEM Calculations Important To Us?

Sustain Quality has a vision for designing sustainable buildings across sectors. We help clients make better decisions, integrate sustainability into their projects and create innovative solutions.

We also aim to make your building process as smooth and efficient as possible, providing you with certification that enables you to achieve completion and compliance.

By reducing energy demand and increasing supply through renewable energy sources, Sustain Quality will enable users to benefit from more sustainable, reliable energy sources in the future. 

If you would like any more information on how we can provide you with energy statements to meet your local authority’s emission target-whether it is an SAP or SBEM calculation-get in touch today.

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